# sample_service.py - Context Documentation

## Purpose

This Python module provides a comprehensive authentication service for handling user login, token management, and session tracking. It serves as the core security component for user authentication workflows, implementing JWT-based authentication with secure password hashing and session management capabilities.

## Usage Summary

**File Location**: `examples/sample_service.py`

**Primary Use Cases**:

- User authentication and login workflows
- JWT token generation and validation
- Password hashing and verification
- Session management and tracking
- Authentication middleware integration

**Key Dependencies**:

- `hashlib`: Used for secure SHA-256 password hashing
- `jwt`: Provides JWT token encoding/decoding functionality
- `datetime.datetime`: Handles timestamp operations for token expiration
- `datetime.timedelta`: Calculates token expiration periods
- `typing.Optional`: Type hints for optional return values
- `typing.Dict`: Type hints for dictionary structures
- `typing.Any`: Type hints for flexible data structures

## Key Functions or Classes

**Classes:**

- **AuthService**: Main authentication service class that encapsulates all authentication logic including token management, password verification, and session tracking

**Key Functions:**

- **create_auth_service(secret)**: Factory function to create an AuthService instance with the provided secret key
- **validate_user_credentials(username, password)**: Validates user credential format requirements (minimum lengths)
- **hash_password(self, password)**: Creates a secure SHA-256 hash of the provided password
- **verify_password(self, password, hashed)**: Verifies a plaintext password against its stored hash
- **generate_token(self, user_id, expires_in)**: Creates a JWT token for authenticated users with configurable expiration
- **verify_token(self, token)**: Validates and decodes JWT tokens, handling expiration and invalid token cases
- **login(self, username, password, user_data)**: Complete login workflow that validates credentials and creates session
- **logout(self, user_id)**: Terminates user session by removing from active sessions
- **is_authenticated(self, token)**: Checks if a token is valid and corresponds to an active session

## Usage Notes

- Always use the factory function `create_auth_service()` to create instances rather than direct instantiation
- Passwords must meet minimum requirements (8+ characters) as enforced by `validate_user_credentials()`
- JWT tokens have a default 1-hour expiration but this can be configured via the `expires_in` parameter
- The service maintains an in-memory session store - consider persistent storage for production use
- Token validation includes both JWT signature verification and active session checking
- Failed authentication attempts return `None` rather than raising exceptions
- The service uses SHA-256 for password hashing - consider upgrading to bcrypt for production use

## Dependencies & Integration

This authentication service is designed to be integrated into larger applications as a middleware component. It expects to receive user data dictionaries containing `password_hash` and `user_id` fields. The service can be imported by API route handlers, middleware functions, or other authentication-related modules.

The service operates independently but would typically integrate with:

- User management systems that provide user data
- API route handlers that need authentication
- Session storage systems for persistence
- Logging systems for security auditing

## Changelog

### [2025-06-02]
- Updated `sample_service.py` - please review and update context as needed

### [2025-06-02]

- Context documentation created
- Initial implementation with JWT authentication
- Added session management and password hashing
- Implemented factory pattern for service creation
---

_This document is maintained by Cursor. Last updated: 2025-06-02_
